THE SHORT ANSWER
Six denominations share .900 fineness but not the same fine-gold unit
Compare official fine-gold content, .900 fineness and diameters for six Centenario, Azteca and Hidalgo gold peso coins.
OFFICIAL FAMILY TABLE
Fine gold, alloy fineness and diameter answer different questions
| Coin | Fine gold | Fine grams | Derived gross grams* |
|---|---|---|---|
| 50 pesos Centenario | 1.20565 oz | 37.4999 g | 41.6666 g |
| 20 pesos Azteca | 0.48227 oz | 15.0003 g | 16.6670 g |
| 10 pesos Hidalgo | 0.24113 oz | 7.5000 g | 8.3333 g |
| 5 pesos 1/2 Hidalgo | 0.12057 oz | 3.7501 g | 4.1668 g |
| 2.5 pesos 1/4 Hidalgo | 0.06028 oz | 1.8749 g | 2.0832 g |
| 2 pesos 1/5 Hidalgo | 0.04823 oz | 1.5001 g | 1.6668 g |
*Calculated as official fine-gold ounces × 31.1034768 grams ÷ .900 fineness. This is not a published tolerance or a substitute for calibrated measurement.
MEASUREMENT WORKFLOW
Do not let a matching number become an authenticity verdict
- Identify denomination and official product family.
- Record scale and caliper resolution and calibration checks.
- Compare mass and diameter without rounding away material differences.
- Inspect design, edge, surface and provenance.
- Escalate unresolved conflicts to an appropriate complementary method.
SIZE DECISION
Smaller denominations trade divisibility for percentage cost
The 2-peso coin contains about 4% as much fine gold as a Centenario, so one unit costs less and can be sold separately. That does not make it cheaper per fine ounce. Compare complete ask and executable bid per fine ounce for the exact denomination.
Keep payment method, destination and observation time constant.
FREQUENTLY ASKED QUESTIONS
Mexican Gold Peso Coin Sizes and Weights questions
How many Mexican gold peso sizes are in the Centenario family?
Banco de Mexico lists six: 50, 20, 10, 5, 2.5 and 2 pesos.
Which Mexican gold peso contains the most gold?
The 50-peso Centenario contains 1.20565 fine troy ounces, the largest official fine-gold amount in this family.
Are Mexican gold peso coins 24 karat?
No. Banco de Mexico lists the family at .900 fineness, or 90% gold by mass.
Is calculated gross weight an official tolerance?
No. GoldObserve derives gross grams from official fine content divided by .900. It is not a Mint tolerance or a measured-coin result.
PRIMARY SOURCES
Official product facts with explicit limits
- Banco de Mexico Centenario gold family: product history, fine-gold content, fineness and diameters.
- Official numismatic products catalog: current Centenario-family product records.
Sources reviewed August 12, 2026. Verify the exact coin, date claim, measurements and transaction terms. No mintage, rarity, authenticity or dealer price is inferred.